.257 Weatherby Mag

[The Sodbuster]

A while back I wrote of some difficulty in getting hand loads for my .257 Weatherby to shoot better than factory ammo, which grouped around 1.25" at 100 yds (3 shots).  Am pleased to report I was out at the range today and found that with heavier bullets (115 and 117 grains) and IMR 4350 powder, the gun started shooting like I felt it ought to.  With varying amounts of 4350 and 117 grain Sierra gamekings, 3 shot groups ranged from .555 to .931 inches.  115 grain noslers not quite as tight.  

Question for other Mark V shooters:  Factory ammo I've shot (100 grain hornady round nose) measured around 3.15 inches.  I seated previous, mostly disappointing loads to about 3.17".  Today's much more accurate loads were seated to about 3.24 inches (I think max length is listed as 3.25").  They fit the magazine just fine.  Any thoughts on seating depth in Mark V actions?  I'll repeat some of my more accurate loads at varying depths.

[aulrich]

First off I don't have experience with 257 Weatherby, but :grin: with something as over bore like 257 Weatherby would even slower powders like 4831, 7828 or retumbo give better results.  Again this is just speculation.

[Ramrod]

Sodbuster, do you happen to know the velocity of those loads? I ask because I have heard some .257 Weatherby shooters getting their best accurracy with .25-06 velocity loads. Not a good tradeoff in my book.
Like aulrich just speculated, higher speeds should come from slower powders. But I think your accurracy improvement might be because the bullet is closer to the rifling with the longer cartridges.

[aulrich]

When I got home from work, I looked 257 mag up in Ken Waters "Pet Loads", because IMR 4350 did not seem that far off. And I found somthing interesting, he metioned in the article that while IMR4350 gave decent velocity he stuggled to get good accuracy with that powder.

He seemed to like H4350, which is slower than IMR's version Imr 4831 and H4831.  He recomended H4831 because it gave good results with all bullet sizes

It's something to think about.

[jro45]

I use RL25 in all my 257 WBY Mag loads except the 87gr bullets and with them I use RL22.

[Lawdog]

Ever since I got my .257 Weatherby Mark V(1970) I used IMR-7828 until I tried Hodgdon H4831.  Seem to give a bit better accuracy although I got better velocity with the IMR-7828.  Now I am switching back to IMR-7828SSC as it is giving me even better accuracy and velocity while metering better thru my powder measure.  Anyone shooting large “magnum” type cartridges should give this new powder from IMR/Hodgdon a try.  Lawdog
 

[The Sodbuster]

If I may respond to some of your questions and comments:

My first reloading efforts for this caliber involved Accurate 8700 and 100 gr Sierra gamekings.  Results disappointing (3 shot groups at 100 yards from 1.5" to 3" plus).  Became wary of really slow powders like Reloader 25 and IMR7828 after that.  Tried other combos with faster powders (including H4831SC and W760) and other 100 grain bullets.  Didn't find a magic bullet.

Don't have a chronograph, so I can't determine velocities.  Am pleased with results of 4350 with 117 grainers, but would like to try Reloader 22 and maybe IMR7828SSC (thank you Lawdog).  Will also try the 8700 again with the heavier bullets, and experiment with seating depth.  I'm tight with a buck so I like Reloader 22 over 25 since I could use it in my .270 Win as well.

[MT4XFore]

Sodbuster,
I've been shooting and reloading for the 257 for over 40 years now.  It certainly does shoot best with slower powders, as do most "overbore" magnum type calibers.  Mine shoots most bullet weights ok, but certainly prefers the heavier ones.  My favorite powders are IMR 7828, R22, Ramshot Magnum, and R25.  I dont like Sierra bullets so I load primarily Hornady or Nosler.  I think the new 110 gr. Nosler Accubond will be really outstanding in the 257.  The Hornady 117 gr. SST shoots sub half inch in mine with R25.  Hope this helps.  Good luck,  :grin:

Jim

[Ricci Price]

I have been fighting a ultra h&r 25-06 (no wonder) now for about two months and have noticed that temperature change has alot to do with my accuracy, seems that slower burning powders (imr4831,h4831sc) are showing alot more pressure than they do during the winter months, I shot the gun last winter with imr4831 with decent accuracy, an inch or so, then about two months ago (temp. in the 80's) I started running into pressure problems(2-3 inch groups). Today I was shooting and went back to my pet load of imr 4350 which is pretty hot, and pressure signs were not as apparent (.75 group), don't know if this helps but I think slower powders are fine when it is cold, I guess I need to get a chrony that would tell me alot.

[mt3030]

Ricci Price:
What have you been fighting? A H&R Ultra (no wonder) issue or a 25-06 (no wonder) issue?
Wally